Apparatus for producing and utilizing micro movements in weak-current technics.



J. A. JOHNSEN.

APPARATUS FOR PRODUCING AND UTILIZING MICRO MOVEMENTS IN WEAK CURRENT TEGHNIGS.

APPLIOATION FILED APBHII, 1911. 1,075,786.

Patented Oct. 14, 1913;

2 SHEETS-SHEET 1.

J. A. JOHNSEN.

APPARATUS FOR PRODUCING AND UTILIZING MICRO MOVEMENTS IN WEAK CURRENT TEGHNIGS;

APPLICATION IiLED APB.11, 1911.

1,075,786. Patented Oct. 14, 1913.

2 SHEETS-SHEET 2.

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communication current along a lon UNITED STATES PATENT oFFroE. v

10N 18 ALBERT J OHN SEN, OF COPENHAGH, DENMARK.

APPARATUS FOR PRODUCING AND UTILIZING MICRO KOYR EENQ S IN WEAK-CURRENT rncmvrcs. 1

Specification of Potters Patent: Qfai'Pa, tented Oct, 14, 1913. Application filed April 11, 1911. Serial 1e. 820,267.

To all whom it may concern:

Be it known that I, J ONAB ALBERT JOHN- SEN, of No. 20 Lassoegade, Copenhagen, in

the Kingdom'of Denmark, mechamcal engineer, and a subject of the Kin of Norway, have invented certain-new an useful Improvements in Ap aratus for Producing and Utilizing Micro ovements in Weak-Current Technics; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as Wlll enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

Experiments heretofore carried out to cause a coil, wound armature or other con-' ductor arranged in a ma etic field supplied with local current to e ect movements of such relative magnitude, strength and precision to long distances under the influence of weak current impulses (such for example as telegraph or tele hone currents) as to render it possible, or example in employing a mlcrophone inserted in a local circuit) to send a corresponding but stronlgler e have led to no ractical results. I either has it been possi le for example by .connecting the said con uctors with a membrane) to obtain a perfectly clear reproduction of the communication or by stronger current-impulses to obtain a louder reproduction. On the other hand it has not been found possible by direct transmission of the micro movements to the said conductor (for example by means of a membrane which is spoken onto) to produce induced currents of substantially greater magnitude than ordinary telephone currents for example. The consideration of the possibilities of a practical solution of these problems has led to the conclusion that with apparatus of the said kind which consists of an electro-magnet with a suitable field, a source of current for feeding the same, a conductor movably arranged in the field and connected with a line from which the conductor can either able conductor and either displaced by it or displacing it in the formercase for producmg a relay e e'ct in a local microphone circu1t for example or for direct reproduction of a conversation, in the latter case for the purpose of bein influenced by speech vibrations or the two last-named elements and the elements connected therewith has already been largely done probably in utilizing the ractical possibilities for ready displaceabllity and ease of action and so forth. The only means remaining by which any considerable increase of effect can be obtained therefore resides in the improvement of the two first-named elements. It is certainly surprising that earlier inventors have contented themselves in this field of research not only with electro-magnets, which, as regards the number of the ampere windings and the lines of force come far below the limits of practical possibilities but-even with simple steel magnets, although in accordance with a known electro-physical law the mechanical forces to which a conductor traversed by current is subjected in'a ma etic field are proportionate to the strengt of the field. On the other hand, it must be assumed that the'strengths of the field heretofore utilized, even when the lines of force could only be counted by hundreds, were more than ample for producing the micro efi'ect here in ques--- effect, would either be of no importance or would even reduce the effect. Nevertheless experiments in this connection have demonstrated that-the micro eifect is increased or rather is made practically eificient by in-.

creasing the strength of the field and that by increasing the strength of the field to the limit of practical possibilities effects of unexpected strength and'purity are produced. This is only explainable by the extremely small efiiciency that has latterly been shown' amplitudes or oscillations of a weak current ans utilizing acoustic and similar micro movements of a conductor carrying a weak cur rent in a magnetic field, such a magnetic super-saturation and strength of this field is employed that a minimum flux of about 20000 lines of force. per square cm. or a number of lines of force amounting to hundreds of thousands or even millions concentrated on the weak current conductor are obtained.

Anannular field and the uniform distribution of lines of force running perpendicularly to the windings of a coil axially disnothing special per se if the strong current placeable in the annular field are already known in connection with weak current relays and no protect-ion is applied for on this point generally, but in this connection the invention-- extends only to the employment of such devices in conjunction with strong current magnets; the poles of which are arranged for concentration of the lines of force. Having regard to the greater conductor rendered possible by the invention it is advantageous to employ'for its suspension and that of the other elements (microphone'and the like) connected therewith a special resilient suspension member which permits of producing these large oscillations even at high periodlcities (over-tones) and without producing acoustic effects by reason of their inertia. The membranes heretofore generally employed for similar purposes and analogous resilient supporting devices held at their outer periphery and connected at the center with the oscillating member present a large useless mass or area, by which acoustic eifects due to their inertia are produced, and before all impede the transmission of the over tones which are essential for clearness in the conversation. Relatively thereto the present suspension member is mainly char acterized by the fact that it is held at the center or the middle points by relatively narrow springs or resilient arms while the weak current conductor and the other oscillating members are connected with its outer ends. An apparatus capable of operating in accordance with this principle is broadly characterized by the fact that between the to the windings of a weak current coil axially displaceable in the field and resiliently held in its position of equilibrium, the said coil being magnetically energized or not.

In the accompanying drawing: Figures 1 to 3 illustrate difi'erent constructional forms of a strong current magnet with highly concentrated field in which the weak current coil is axially displaceable (for the sake of clearness this coil is omitted in Fig. 3).

Fig.4'is a top view of the compound magnet shown in Fig. 3. Fig. 5 illustrates the connection of a weak current coil with a local microphone circuit. Fig. 6 shows the combination of a weak current coil with an air action member to a larger scale. Figs. 7 to 9 illustrate various forms of the weak cur- 'rent coil the microphone and the resilient electro-magnetsutilized in experimental physics are compared therewith. This applies more particularly to the form illustrated in Fig. 1 with simple pole cones 1 and 2 directed toward each other. The novelty of the apparatus resides in the fact that the enormous number of lines of force (mainly ago-shaped) proceeding from the pole cones, t

at'is to say, from their points act at favorable angles on a coil 3 displaceable'axially,

thatis to say, from one pole to theother of double conical-formation and inserted in the weak current line 4, 5, a telegraph or telephone line for example. The number of the ampere windings on the magnet coils .6 and 7 may be from 2000 to 20000. The current can be taken from an ordinary town main or from a lamp socket or itmay be produced by a special source of current 8.

In the drawing the coils stop at the foot of the base of the cone; in practice it is, however, preferable to allow them to-extend almost to the apex of the cone, that is to say, to the limit of the field with which it is desired to operate,

Fig. 2 illustrates the magnet cores surrounded-by a magnetizing coil 6 common to them all. 1 The pole 2 is in the form of a hollow cone inclosingthe pole point 1 in such a manner that a concentrated and relatively very small field of conical annular form is produced in which the correspondingly small conical weak current coil, 3 is displaceable axially.- Behind the hollow cone'a chamber 9 is provided for the reception of the apparatus (a microphone for example) with which the coil 3 is to be connected. In order that the magnetic field may remain accessible one of the cores such as the core 2,'can be arranged in such a manner that it can be removed through the lateral part 10 or together with it.

While the fields illustrated in Figs. 1 and 2 are uniform that is to say, they theoreticallypresent the same magnetic intensity at every point located at the same radial distance in a'plane erpendicular to the axis of the field'the' field shown in Figs. 3 and-4 is .open at difier'entplaces. This field is formed between the pole cone 1" and two or more pole points 2" arranged} perpendicu position in which the vlongitudinal axis of the points and of the corresponding iron cores are erpendicular and their pole faces arallel; romthe front to .the generating ines of the cone 1". In accordance with Fig.

3 the points 2 are providedwith recesses or notches 11 the ole faces of which run parallel with the po e face 1. On the upper side the can be provided with wider recesses 12 which serve to prevent dispersion ofthe lines of force. In the field acoil 3" (Fig. 2) can be arranged. However, when using three, four or more pole points 2 a coil of pyramidal form with a trian lar, quadrangular or. other polygonal ase can be used, the pole point 1 being made of corresponding pyramidal form.

The magnet shown in section in Fig.- 5 is either an entirely closed bell or iron inclosed magnet or provided with an open frame as shown in igs. 3 and 4 only the coils 7 being omitted and their cores united to form a single part 13. Preferably the magnet comprises a central 0 enin the form of which corresponds to t at o the ole point 1 of the magnet 6 orelse (Fig. 5 a larger opening in which a special annular pole piece 2 is arranged. T e weak current coil 3 interposed on the line 4, 5 isconnected with a rod or spatula-she. ed member 15 for example by means of insu ated arms 14, this member 15 being inclosed in a receptacle 16 containing granular carbon. This microphone 15, 16 is connected up with the pri mary winding 17 of an induction apparatus in a local circuit 18. Aline wire 20, 21 can proceed from the secondary winding 19. Fig. 5 therefore represents an embodiment for the employment of the invention as a weak current relay. It will be noted that the coil 3 inserted in the magnet field in such a manner as to be axially displaceable in a-suitably resilient manner is acted u on under the influence of the current impu ses coming from the line 4?, 5 toward. one or other of the poles away from its position of equilibrium. The spatula-shaped member 15 will participate in these micro movements. In agreement herewith the resistance constituted by the carbon bodiesor the like between the member 15 and the conducting wall 22 of the receptacle .16 and also the strength of current in the induction ap aratus 17, '19 and the ,line v20, 21 is mo ified. Any other suitable form of microphone can be employed in place'of that here illustrated. The microphone 15, 16 illustrated could be formed in duplicate'by-arranging the other wall 22 of the race tacle 16 as a conductor and insertin it in t e primary circuit 17 as indicated. hen on the right hand side of the microphone electrode 15 (owing to, its

' movement toward the right hand) a diminution of the resistance and therefore an increase in the strength of the current in the branch line 18 takes place, simultaneously on the left hand of the microphone electrode an increase in the resistance and therefore a weakemng of the current in the branch line 18 will take place. By suitably connecting the secondary coils 19 and '19 in series or in parallel both actions are rendered cumulative.

In Fig. 6 the coil 3 is connected with a membrane or a plate 23 which causes the air to vibrate directly as in a telephone receiver or which, inversely, is displaced -by the vibrations of the air and is thus able to displace the coil 3 whereby a current such as an acoustic operated current for example is induced in the line 4, 5 24 is a sound horn and 25 a casing surrounding the plate 23 in which the latter is freely displaceable, somewhat in the manner of a piston. 26 are rods connecting the coil 3 with the plate 23.

In order to avoid dispersion of the lines of force, that is to say in order to obtain the maximum concentration of the lines of force in the field, a 'coneshaped recess 12 is provided externally upon the pole piece 2 and corresponds to the recess shown in Figs. 3 and 4, while the inner side is provided with a conical face 30. The pole face proper 1 of the other pole protrudes somewhat in front of the annular cone 31 arranged between it and the thicker core. The material is also removed from the center of the point so that a conical or hemispherical recess 32 is formed. The magnetizing coil-mustextend almost to the head 1. In particular, generally speaking in all these apparatus the magnet frame must be wound as far as possible and the iron cores made as long as possible. In order to avoid Foucault or eddy currents in the poles they are preferably recessed so as to interrupt the continuity of conduction on their outer stratum.

Fig. 6 illustrates by way of examplea spherical field. With this object the coil 3 presents the form of a hemispherical shell.

V it is arranged in the pole piece 2 and convided with a resilient supportin nected by a rod 28 with another plate 20 secured to the coil, The plates 27 and 29 or one of them are made resilientor formed as suspension members. in the manner indicated above. The rods 26 pass freely through the plate 27. If desired the plate 23 can be omitted, in which case its purpose is served by the membrane--27 which is -fixed at its periphery or at the ends. In this case the 1 rods 26 are also dispensed with or their,

outer ends are connected with the plate 27 one-end of the suspension-member 29 which in this figure lies horizontally, in such a manner that during the movements of the coil 3 the grains of carbon are displaced with it. In this case the other pole 15 of the I microphone is secured in some appropriate manner. I

Figs. 8 and 9 illustrate a cylindrical coil, which is employed when the faces of the pole pieces, which are directed toward theu field and also toward each other, are cylindrical, the coil 3 being made cylindrical to correspond. The resilient suspension member 29 is provided in this figure at each end with a microphone electrode 15 each of them working in its granular carbon receptacle 16. The two microphones can be connected in series or parallel in suitable local circuits such as 17, 18 (Fig. 5). The freely resilient arms 36 of the suspension member 29 held at the middle, are connected with the coil by means of laterally bent projections 37, lugs, bolted rods or the like.

Fig. 10 shows a spring provided with very long arms 36 and Fig. 11 a spring with three arms 36.

Figs. 12 and 13 show how a spring which is long in itself can be caused to oscillate with relatively short arms 36 by utilizing two or more screws 34. or the like (Fig. 12) or by employing a separate plate 38 (Fig. 13) which retains or damps the middle portion beyond a given length. A similar damping can also be produced by using a fiat spring by twisting it so that its middle portion is turne on edge.

The springs or their arms 26 shown in Figs. 6-13 need not be flat; they might equally well be round or hollow or present other suitable cross sections. The arms 36 need not be connected one with the other at a common center, buteach may constitute an independent spring in cases when more than one 1s provlded, 1n such a manner that ime-nee tones due to inertia are avoided. These two or more springs-can be secured at a common fixed point, or ata number of difierentfixed points. 4 The form of the field and of the coil can of course ,be modified in various ways as regards profile andcross section. They can be straight, broken or curved in profile and the cross section may be round, oval, polygonal and soforth.

What I claim and desire to secure by Letters Patent .015 the United States is 1. An apparatus for producing and utidizing acoustic and similar micro displaceifients of a coil carrying a weak current in a concentric magnet field, comprising a magnet field constituted by strong current electro-magnets and a coil carrying a weak current, t e diameter of said coil being smaller than the diameter "of the core of the concentric magnet, and said core bein provided with a concentration pole whic closely surrounds saidcoil. 3

--2; An apparatus for rendering the movementsof a conductor carrying a weak current i-na magnetic field capable of practical utilization comprising'the combination with an electro-magnet having conical pole pieces for concentrating the hues of force of an axially displaceable conductor carrying a weakcurrent situated in said field and connected to the ends of sprin s held in place at central points and constituting a reproducing device.

3. An apparatus for rendering the movements of a conductor carrying a weak current in a magnetic field capable of practical utilization comprising the combination with an electro-magnet having concaye and convex cone shaped pole pieces in proximity to each other of a resiliently retained conductor carrying a weak current axially'displace able in ,the concentrated field induced by the said magnet poles and connected through intermediate members with a microphone.

4. An apparatus for producing and utilizing acoustic and similar micro displacements of a coil carryin a weak current in a concentric magnet fiel comprising a relatively smallcoil and a field constituted by means of large strong current electro-magnets provided with concentration poles, and a resilient bar secured in the axis of said poles and extending transversely over said concentrated field, said coil bein suspended .from said bar as a freely mova le body in said field.

. 5. An apparatus :tor producing and utilizing acoustic and similar micro displacements of a coil carrying a weak current in a concentric magnet field, comprising a relatively small coil and a field constituted by ,means' of large strong current electromagnets provided with concentration poles,

I a resilient bar secured in the axis of said In testimonytliat 'I claim the foregoing; poles and extending transversely over said as my invention, I have signed my name concentrated field, said coil being suspended in presence of two subscribing witnesses.

from said bar as a freely movable body in v JONAS ALBERT J OHNSEN. 5 said field, and a microphone electrode also Witnesses: I I J suspended fromsaid bar as a freely movable ERNEST BOUTARD,

body. P. Hon'm BARv. 

